Musnad Ahmad 31:666

Hassan ibn al-Rabi‘ narrated to us, he said: Ja‘far ibn Sulayman narrated to us, from ‘Ali ibn ‘Ali, from Abu al-Mutawakkil, from Abu Sa‘id al-Khudri, who said: When the Messenger of Allah (may Allah bless him and grant him peace) would begin the prayer, he would say: "Glory be to You, O Allah, and with Your praise, and blessed is Your name, and exalted is Your majesty, and there is no god other than You."